RasoolAllah did indeed spare many munkir like Abdullah bin Obey. But that was what separates him from his Ummati.
Unlike Ahmedies we believe in the finality of Muhammad Rasoolallah. We are not like you, we know we can never be like Rasoolallah. The only thing that can save Ahmedi's is if Rasoolallah himself or any of his ahle bayt order us to stop killing Ahmedies.
We are not nabi's we cannot show forgiveness. We are mere foot soldiers who hold no power, we follow Rasoolallahs and his khalifas and the Ahle Bayt. Anyway according to Islamic teaching a man who insults Allah can be spared, if he repents. That is becuase it was not exactly a crime we can sort out. It's up to Allah on this matter.
However to Insult Rasoolallah is not just a crime against Allah it is also a crime against the followers. like a crimanl can claim forgiveness for murder, Allah might forgive him but the Law requires him to be put to death. By slandering the prophet a munkir who reads kalima has lost his right to be called a muslim but furthermore he has broken a law punishable by death. Why read the kallima if you don't believe it.
As for munkir's namaaza Musailama and co also read namaaz, were they spared? No forty thousand of his followers were massacred in a day. What made the riddah wars so bloody was in the words of Abu bakr:
"Up till now we have fought munkir of Allah, we have been defending ourselves from thier attacks becuase that is what rasoolallah told us to do.
Our nabi has left us now, and his enemies march upon us while we sit here.
Oh veterans of Badr hear me! what use is sitting here if they can insult our lord. Today we shall not wait for them to come for us, we shall march to them and fight an agressive war the likes of which has never been seen in the Hejaz!
Let us shows these munkirs and those who follow them that we shall show no mercy to anyone who speaks against the one we love! Today they slander the man who has spared them so long. We will not spare one of them!
Abu Bakr acted with full authority and clamped down on the apostates. It doesn't matter that they spoke arabic and read namaaz becuase even if they hid in the kabbah they would not be spared from the swords of fury.
In that time the Sahaba showed no objections so we as Muslims must show no mercy to the Ahmedies and Wahabi's.
Ahmedies should renounce thier treachery. It would not be so bad for them if they were worshiping any false god. Trouble with these apostates is that they have betrayed Rasoolallah and his deen by speaking against him while claiming to be part of it. Any religion would destroy the traitors within its ranks otherwise it's power is reduced.
So no suprise Ahmedies are treated like this.
Besides why did they have to start this new religion anyway?
We all know it was to undermine Islam from within.
I'm sorry at any loss of life, but at least we have Rasoolallah to pray for us and save us from Allah's wrath when we soak the earth with apostate blood. Tell me by betraying him who will save the Ahmedies....... Mirza?